Surface heating system and method for producing it and a heatable object

ABSTRACT

A surface heating system consists of a support and a heating layer that contains an electrically conductive plastic. The heating layer is formed by a flexible film. A heatable object made as such a surface heating system. A method for producing a surface heating system, where a heating layer containing an electrically conductive plastic bonded to a support, and where the heating layer is formed by initially applying an electrically conductive, especially a foam plastic material onto the support and then hardening the plastic material on the support. Alternatively, the method produces a surface heating system with a heating layer of an electrically conductive plastic is bonded to a support. The heating layer is produced from an electrically conductive, especially a foam plastic material, and then arranged on the support. Another alternative of the method consists of bonding a heating layer with an electrically conductive plastic to a support. A fabric is produced as the support. Contact terminals from power supply wires are woven into the fabric when it is made or afterwards, and then a heating layer is applied to the support and the contact terminals.

RELATED APPLICATION

[0001] This application is a continuation of PCT InternationalApplication No. PCT/DE01/04879, filed Dec. 21, 2001, the contents ofwhich are here incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a novel surface heating system, aheatable object with the novel surface heating system and a method forproducing the novel surface heating system. More particularly, thisinvention relates to a seat heating system, a heated seat and a methodfor producing it. Preferably, the invention additionally relates to aheating system for side panels and floor coverings, in particular inmotor vehicles, side panels and floor coverings outfitted with suchheating system in particular in motor vehicles and a method forproducing them. Furthermore, this invention relates in particular to amattress heating system, a heated mattress and a method for producingit.

[0004] 2. Prior Art

[0005] Seat heating systems are known from practice, for example, formotor vehicles; these systems in the sense of the invention are asurface heating system and are formed by current-carrying metallicconductors as heating wires that are arranged between cushion layers.This necessitates not only a costly construction of an appropriatelydesigned seat, but it also has disadvantages in particular in operation.For instance, because of the stronger heating of surrounding layers inthe immediate vicinity of the heating wires there is a danger ofoverheating, which can lead to damage to the cushion layers and/or theheating wires and even cause a fire. Furthermore, the heat distributionover the area is not optimum, since the temperature is always higher inthe region of the heating wires than at a distance from them. Alsodisadvantageous with this known style is the mechanical stress to whichthe heating wires are subjected when a passenger uses the seat, sincethe conducting wires can break because of this, which can lead tofailure of operation and/or can have as a consequence another source offire.

[0006] A composite heating element that provides a directed heatradiation and is formed of a plastic laminate with incorporation of asemiconducting layer is known from DT 26 16 771 A1. This laminateconsists of a hard plastic laminate structure that is formed of at leastone layer of a reinforced substrate base material and a resin coating onthis material, a semiconducting carbon containing a pyropolymer, whichis bonded to a heat resistant inorganic oxide support with large surfacearea, which is incorporated as a layer on at least one side of the layerof the substrate material, a heat reflecting layer incorporated on thesubstrate material in a position on one side of the pyropolymer, andpower supply devices to spaced parts of the layer of conductivecarbon-containing pyropolymer, and which produces electrical resistanceheating in the laminate, which is reflected and radiated by the heatreflecting layer of the laminated element. Such heating panels areintended to be used as part of a wall of a living space or office.

[0007] With this prior art the incorporation of the semiconducting layerinto the laminate can take place by mixing finely dividedcarbon-containing pyropolymer in the form of small particles or aspowder with a suitable carrier or vehicle, which can be brushed, spreador otherwise applied to the surface of a resin coated glass cloth ofpaper, felt, cardboard and the like as laminate substrate or to a woodveneer that is used in the laminate panel. Instead of this, the finelydivided carbon-containing pyropolymer can also be mixed with the resinor polymer material with which a particular reinforcing base material isto be impregnated or that is to be applied to this base material as acoating, where this base material provides at least one substratematerial of the laminate. The resulting mixture is applied into or ontothe substrate by immersion or coating, and the resulting coatedsubstrate is subjected to a semi-hardening such that the semiconductingpyropolymer produces a uniform impregnation and coating over theresulting semi-hardened laminate sheet.

[0008] DE 33 16 182 A1 concerns the use of molded articles like films,or panels or three dimensionally shaped articles from the class of thepyrrole polymers that are complexed with anions, as electrical heatingelements in particular for heating corroding liquids or gases. Themolded articles can also be coated with organic plastics.

[0009] A polymer composite heating element is described in DE 35 24 631A1 and has the form of a film, tube or rod. Such polymer compositeheating elements can be used as heating elements as such or can belaminated with traditional plastic films in order to improve thestrength of the material.

[0010] The use of electrically conductive thermoplastic polyurethanesand their preparation are known from DE 33 21 516 A1. The correspondingproducts are suitable, among other things, for the preparation of 1-2 mmthick films for surface heating elements.

[0011] Thus, heating elements with electrically conductive plastic areindeed known, but in all of the prior art there is no data or hints ofhow such heating elements are to be designed and produced in order to beable to use them in practice.

[0012] Surface heating systems that have a layer of electricallyconductive plastics are illustrated in a number of other publications ofthe international patent classes H05B 3/36 and 3/84 using the outsidemirrors of motor vehicles as examples. Essentially, films ofelectrically conductive plastics on solid supports are used in thiscase. The use of a film of electrically conductive plastics on thesupport structure of a vehicle seat, however, is not possible, since allthe cushion layers lying on top, etc., would have to be heated for theheat to reach a sitting passenger, which would involve a great deal ofenergy.

[0013] In particular for sitting or reclining supports there are noknown usable surface heating systems with electrically conductiveplastics. However, simple, inexpensive and safe heating systems would bedesired, for example, for vehicle seats or mattresses.

SUMMARY OF THE INVENTION

[0014] Therefore, one goal of this invention is to create a surfaceheating system with an electrically conductive plastic as well as anobject using it with cost that is as low as possible.

[0015] This goal is achieved with a surface heating system, a heatableobject and a method for producing a surface heating system as describedhereinafter.

[0016] As other advantages, a good, simple and operationally safe designand good heat distribution are enabled with the invention.

[0017] In accordance with the invention a surface heating system with asupport and a heating layer that contains an electrically conductiveplastic is created, where the heating layer is formed by a flexible filmand the support is flexible.

[0018] Such a surface heating system is further developed within thescope of this invention by the fact that the support is a layer, inparticular a woven or nonwoven material, preferably a natural orsynthetic fiber nonwoven material. Alternatively, the carrier can be amolded article of an elastic material, for example a seat cushion of aseat bottom or a seat back, or a mattress.

[0019] Preferably the heating layer contains polyurethane, one-componentpolyurethane, crosslinked one-component polyurethane, a PU foam,UV-resistant and/or hydrolyzable and/or vapor-permeable plasticmaterial. However, other electrically conducting or conductive foamingand foam materials are also usable, where plastic materials arepreferred. Alternatively or additionally, it is preferred that theelectrically conductive plastic of the heating layer contain graphite,preferably in powder form.

[0020] It can be further provided in the surface heating system thatcontact terminals from power supply wires in the heating layer orbetween the carrier and the heating layer be in contact with the latter.Preferably, the contact terminals of the power supply wires are affixedto the heating layer by means of the heating layer itself or arestitched or glued to the heating layer and/or the support.

[0021] In addition, it is advantageous for the heating layer to beformed directly by spraying, rolling or spreading on the support.Alternatively, the heating layer can be glued, stitched or welded to thesupport or can be affixed to it in other ways.

[0022] Furthermore, it is advantageous to design a manually and/orelectrically/electronically operable and/or automatic current controlthat can be connected to a power source and hooked up to the currentconducting wires whose contact terminals are in contact with the heatinglayer.

[0023] In addition, through the invention a heatable object is createdthat contains a surface heating system in accordance with the abovedevelopments.

[0024] Within the scope of a preferred design the object is a seatbottom or a seat back or a cushion of furniture for sitting orreclining, especially a mattress, and the heating layer is anatomicallymatched to the thigh/buttocks regions or the back regions of a user. Thelatter is advantageously achieved by anatomically molding the heatinglayer in the plane of the seat bottom or the seat back or the cushion ofsitting or reclining furniture, especially a mattress, by it beingpresent or electrically conductive only in accordance with anatomicalguidelines. Alternatively or additionally, the heating layer can have athickness profile corresponding to anatomically matched heat release.

[0025] Another preferred design of the heatable object consists of anupholstered lining or paneling, especially for a vehicle. Such aheatable object can also be designed for different heat release over itsarea.

[0026] Generally, it can further be provided that the heating layer isprofiled for different heat release over its area in its areal extentand/or in its thickness.

[0027] Finally, this invention also creates a method for producing asurface heating system, where a heating layer with electricallyconductive plastic is bonded to a support. In accordance with theinvention the heating layer is formed by first applying an electricallyconductive, especially foaming or foam plastic material onto the supportand then hardening the plastic material on the support. A preferablefurther development of the method consists of initially arrangingcontact terminals from power-supply wires on the side of the support onwhich the plastic material will be applied, before applying theelectrically conductive, especially foaming or foam plastic material tothe support.

[0028] It is provided in a method in accordance with the invention forproduction of a surface heating system, where the heating layer with anelectrically conductive plastic is bonded to a support, the heatinglayer is made of an electrically conductive, especially a foaming orfoam plastic material, and then arranged on the support. Preferably,after being arranged on the support, the heating layer can be bonded tothe support so that it will not slip. This preferably takes place bystitching, gluing or welding the heating layer to the support.

[0029] Electrically conductive polyurethane is advantageously used asthe plastic material, but the plastic material is not restricted tothis.

[0030] The method can be developed further by the fact that the contactterminals from the power supply wire are attached to the heating layerand/or the support so that in the sandwich of support and heating layerthey are in contact with the heating layer. For this the contactterminals from the power supply wires are preferably stitched or gluedto the heating layer and/or the support.

[0031] Another further development of the method in accordance with theinvention consists of the heating layer being profiled in its surfaceshape and/or thickness during or after its manufacture. This can takeplace in the manufacture of the heating layer directly on the support,for example by means of templates that determine the surface shape ofthe heating layer. If the heating layer is manufactured separately,i.e., not directly on the support, its shape can be produced, forexample, by molding or by stamping. The thickness over the area of theheating layer can also be varied.

[0032] Preferred and advantageous further developments result from thedependent claims and their combinations and the overall content of thedisclosure of this document and taking into account the knowledge ofspecialists and the prior art, in particular to the extent that it ispresented in the introduction of this description.

[0033] For example, the electrically conductive plastic material of theheating layer can contain carbon or carbon particles in order to makeavailable electrical conductivity. Otherwise, the material of theheating layer is such that it remains at least essentially hardened andotherwise shape stable and undamaged at or after an increase oftemperature as a consequence of the heating effect. As already noted,polyurethane (PU) is preferably used for the electrically conductiveplastic, but basically all of the other materials disclosed in the priorart indicated above insofar as they can be foamed, are also usable.Other material data and technical background are disclosed, for example,in the publications DE G 85 23 328.5, DE 298 08 842 U1, DE 197 11 522 A1and DE 691 01 703 T2, whose contents are hereby fully incorporated byreference into these documents in order to avoid mere repetition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention is illustrated in more detail below by means ofembodiment examples, which are represented in the drawings, in which:

[0035]FIGS. 1a and b show schematically in a sectional or perspectiveview a first embodiment example of the invention in connection with avehicle seat with seat heating,

[0036]FIGS. 2a and b show schematically in a sectional or perspectivepartial view a vehicle seat with seat heating according to the priorart,

[0037]FIGS. 3a, b and c show a second and a third embodiment example, asurface heating surface in accordance with the invention schematicallyin a perspective overview representation and a sectional view inconnection with an interior trim panel of a vehicle,

[0038]FIGS. 4a and b show schematically an interior trim panel cover ofa vehicle as a fourth embodiment example of a surface heating system ina perspective overview drawing and a sectional view,

[0039]FIGS. 5a and b show schematically a fifth embodiment example of anobject with a surface heating system in a perspective overviewrepresentation and a sectional view in the form of a floor carpet for avehicle,

[0040]FIG. 6 shows schematically as a sixth embodiment example of theinvention a vehicle seat with seat heating in a perspective partial viewand

[0041]FIG. 7 shows in section another embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0042] The same reference numbers are used throughout for the same orequivalent parts in the following description of the invention using theembodiment examples. Even though not all details of the graphicrepresentations are treated in the following description the individualcharacteristics and their relationships to the extent that they arerepresented in the figures easily follow for a specialist from thedrawings.

[0043] As a first embodiment example of a surface heating system 1 avehicle seat 2 in which a seat heating system 4 is integrated into itsseat bottom 3 is shown in FIGS. 1a and 1 b in a sectional andperspective view.

[0044] The construction of the seat bottom 3 in the vicinity of thesurface heating system 1 is shown in FIG. 1a, in which a cross sectionthrough the corresponding layers/components of the seat bottom 3 isshown. The surface of the seat bottom 3 is formed by a seat cover 5,which can consist of fabric, synthetic leather or leather or othersuitable materials or combinations of materials. The shape of the seatbottom 3 is formed at least essentially by an elastic foam molded body6. The components of the seat heating system 4 are arranged between theelastic foam molded body 6 and the seat cover 5.

[0045] The seat heating system 4 is formed by the surface heating system1, which contains a heating layer 7 and a support 8. The support 8 is aflexible layer of a fiber nonwoven with natural and/or synthetic fibers.The heating layer 7 consists of a flexible electrically conductiveplastic foam, for example electrically conductive polyurethane, fromwhich a film or foil has been formed, so that a surface skin isproduced. The film does not have any detectable pores, but in itsmicrostructure can be close-celled or close-pored. In particular, thematerial is UV-resistant and/or hydrolyzable or vapor-permeable, inorder to be used in accordance with the best use in furniture forsitting or reclining. In this way optimum conditioning of air throughthe base is ensured for the user.

[0046] The material for forming the film, for example UV resistant andhydrolyzable or vapor permeable crosslinked one-component polyurethane,is applied to the fiber nonwoven by spraying, for example, so that aso-called spray flush or spray skin is formed by this so-called sprayflush method. Alternatively, the film could also be applied to the seatcover 5 or the elastic foam molded body 6 by this method. The materialcould also be sprayed into the foam mold for the elastic foam moldedbody 6 before introducing the foam material in order to bond with thefoam material as it hardens. When producing the film by spraying, thethickness of the film can be precisely adjusted and optionally variedover its extent by means of the spray time, for example. Alternatively,the film can also be produced by rolling or spreading the correspondingmaterial in particular on the support 7, but also it can be producedseparately, and then bonded to the support 7, the seat cover 5 or theelastic foam molded body 6.

[0047] Between the heating layer 7 and the support 8 contact terminals 9and 10 from power supply wires 11 or 12 are placed at the edge of theheating layer 7 so that they are in electrical contact with the heatinglayer 7 (see also FIG. 1b).

[0048] To produce the surface heating system 1 of the first embodimentexample, flowable or flowing electrically conductive polyurethanematerial that contains, for example, carbon particles as illustratedabove, can be applied to the fiber nonwoven material of the support 8 byrolling, spreading or spraying, after the contact terminals 9 and 10 ofthe power supply wires 11 and 12 have been appropriately positioned onthe fiber nonwoven material of the support 8. After hardening theelectrically conductive polyurethane foam it is flexible and inelectrical contact with the contact terminals 9 and 10 of the powersupply wires 11 and 12 and forms the heating layer 7. The contactterminals 9 and 10 of the power supply wires 11 and 12 can be held inposition just by the bonding forces between the polyurethane foam andthe fiber nonwoven. For further assurance that they are secured thecontact terminals 9 and 10 of the power supply wires 11 and 12 can alsobe stitched to the sandwich (not shown). In this variation theelectrically conductive PU layer of the heating layer 7 is at the sametime also an adhesive or gluing layer.

[0049] Instead of forming the heating layer 7 directly on the fibernonwoven of support 8, the heating layer 7 can also be producedseparately and joined with the support 8 in a hardened, but flexiblestate. The connection between the heating layer 7 and support 8 takesplace, for example, by gluing, stitching or welding, in each caseaccording to what mode of processing can be carried in dependence on thematerials that are used. The contact terminals 9 and 10 of the powersupply wires 1 1 and 12 do not necessarily have to lie between thesupport 8 and the heating layer 7, but rather can also be applied to theside of the heating layer 7 turned toward the support 8 in order toobtain electrical contact.

[0050] The fiber nonwoven of the support 8 can also initially be aribbon material on which the heating layer is formed over its completesurface or in correspondence with the geometry necessary for the seatbottom 3, or the pre-made heating layer 7 can also be laid on it asribbon material or as parts molded in correspondence with the geometrynecessary for the seat bottom 3 and then bonded to it. Then the desiredindividual pieces in correspondence with the geometry necessary for theseat bottom 3 can be produced, for example, by stamping. However, it isalso possible for the fiber nonwoven first to be made in the geometrynecessary for the seat bottom 3 and to form the heating layer 7 on it,which can also be pre-made in correspondence with the geometry necessaryfor the seat bottom 3. The contact terminals 9 and 10 of the powersupply wires 11 and 12 can, in making the sandwich of support 8 andheating layer 7 in each case as suitable, be laid between them orarranged on the at least assembled sandwich so that they can be suitablysecured.

[0051] In FIG. 1b the first embodiment example of the surface heatingsystem 1 is illustrated further in a schematic perspective view in whichthe seat cover 5 is omitted. Here the layout of the contact terminals 9and 10 of the power supply wires 11 and 12 can readily be seen. Inaddition a power control unit 13 and a power source 14 for control andoperation of the surface heating unit 1 are also shown schematically.The power control unit 13 can be manually and/orelectrically/electronically and/or automatically operable. In practicethe power control unit 13 is the usual control of the temperature of thepassenger compartment or a part thereof or a separate control. The powersupply wires 11 and 12 are connected to the power control 13 and more orless end at their contact terminals 9 and 10. In front of the contactterminals 9 and 10 there can be, for example, a functioning unit 15 onthe power supply wires 1 1 and 12, which can contain, for example, aspecial seat occupancy sensor, a heat sensor or temperature gauge, adistributor, etc.

[0052] The support 8 could be formed of other materials and structuresinstead of a nonwoven material, for example a woven material. Thesupport 8 however, could also be a molded article, for instance theelastic foam molded article 6 itself of the first embodiment example inaccordance with FIGS. 1a and 1 b.

[0053] Suitable materials for the heating layer, i.e., the electricallyconductive foam material, are specified in the supporting documents,especially with regard to their physical properties, and are otherwisewell known to the specialists, and are also indicated, for example, inthe prior art that is cited in the documents at hand, so that there isno need to go into this subject in more detail, but rather all suitablematerials, especially from those cited in the documents at hand or thecited older publications are hereby incorporated herein by reference.

[0054] Although it is not illustrated above and also not shown in FIG.1b, the seat back that is only partly visible in FIG. 1b can also beoutfitted with a surface heating system 1. Furthermore, all similarobjects without restriction, especially mattresses or other cushions,can be outfitted with a surface heating system in accordance with theinvention. A use of the invention in side panels and floor coverings inparticular in vehicles, is preferred.

[0055]FIGS. 2a and 2 b show representations by analogy with FIGS. 1a and1 b simply to illustrate the differences of this invention to the priorart. This known surface heating system 1 in the form of a seat heatingsystem 4 for a vehicular seat has, in the usual way, the seat cover 5and an elastic foam molded body 6, between which the surface heatingsystem 1 is situated.

[0056] In the prior art, the surface heating system 1, as FIGS. 2a and 2b illustrate, contains, starting from the seat cover 5, an upper fabriclayer 17, an upper foam layer 18, a heating wire layer 19, a lower foamlayer 20 and a lower fabric layer 21, which as a prepared sandwich arebonded to the foam molded body 6 that forms the actual seat cushion sothat they will not slip using a double sided adhesive strip 22.

[0057] In the production of this surface heating surface in accordancewith the prior art the fabric layers 17 and 21 are first bonded to theimmediately adjacent foam layers 18 or 20 in a flame lamination process.

[0058]FIGS. 3a, 3 b and 3 c, 4 a and 4 b and 5 a and 5 b present furtherembodiment examples of heating devices for vehicles.

[0059] In FIG. 3a a vehicle K is shown in a cutaway view, in which acutting plane A through an interior panel 23 of a car door 24 is shown.The schematic sectional view of the interior panel 23 in cutting plane Ain accordance with the arrows shown in FIG. 3a is shown in FIG. 3b as asecond embodiment example of a heatable object with a surface heatingsystem 2. This interior panel 23 contains as support 8 a support layer24, on which the heating layer 7 with electrically conductive plastic isapplied by means of an adhesive agent 25. Since the visible surface ofthe interior panel 23 is formed by the heating layer 7 with electricallyconductive plastic, the free visible side 26 of the heating layer 7 withelectrically conductive plastic can be provided with a decoration (notvisible), i.e., with a synthetic leather like appearance, in order toachieve a pleasant appearance for the interior panel 23.

[0060] Alternatively to this embodiment example, in a variation thereof,which is shown in a cross section in FIG. 3c, the heating layer 7 withelectrically conductive plastic can be applied to the side of thesupport layer 24 that is turned toward the inside 26 of the vehicle Kusing adhesive 25. In such a case either the support layer 24 itself canbe provided on its visible side with a decoration (not shown) or adecoration 27 (only partly suggested for the sake of better clarity) canbe applied to the visible side of the support layer 24.

[0061] The principle of the two embodiment examples just described canbe extended to the entire passenger compartment 26 of the vehicle K,especially to the extent that the corresponding parts are upholstered.For example, vehicle seats for realization or support of seat heating, aroof lining, a rear shelf, column liners, consoles, a steering wheel,carpet material, air channels, especially within air channels forpreheating cold air, etc., can be used as heatable objects with heatingdevices that contain a heating layer 7 with an electrically conductiveplastic, to improve the interior climate in a vehicle. In this way it isnot only possible to make the conventional heating plants smaller, butalso to achieve faster and more uniformly distributed or achievedheating of the entire interior space 26 of a vehicle K. Other specificembodiment examples of this are illustrated in FIGS. 4a and 4 b and 5 aand 5 b.

[0062] In a perspective of a instrument panel 28 and console 29 FIG. 4ashows the position of a cutting plane B, where the viewing directiononto the cutting plane is illustrated by arrows in the representation inFIG. 4b. FIG. 4b is the section through the instrument panel 28 incutting plane B, where a part of the adjacent windshield 30 of thecorrespondingly outfitted vehicle K is also shown in the cross section.The heating layer 7 with electrically conductive plastic forms theplastic skin with which the instrument panel 28 is covered and thatforms the surface of the latter. By means of an adhesive agent 25, whichin this fourth embodiment example is formed by a filling compound likefoam, etc., the heating layer with electrically conductive plastic isbonded to a support layer 24 in the capacity of carrier 8 that serves asspacer 31. The heating layer 7 with electrically conductive plasticforms a skin with incorporated conductive material. Alternatively, inthis embodiment example the heating layer 7 with electrically conductiveplastic could also be covered by a decorative layer (not shown), forexample analogous to the variations shown in FIG. 3c.

[0063] In FIG. 4b a windshield 30 is shown in part in cross section as afurther embodiment example of an object with a surface heating system 1.This windshield 30 is provided with a black ceramic layer 32 in theregion where it begins which can be applied, for example, by silk screenprinting. In addition, it is provided that in the region of the ceramiclayer 32 a heating layer 7 with electrically conductive plastic isaffixed to the windshield 30 directly or by means of an adhesive agent25, for example a glue. Through this embodiment it is possible, forexample, to realize an ongoing additional and/or separate heating of thewindshield 30 in order to prevent fogging, for defogging or for deicing.In addition, such a surface heating system 1 can be provided inparticular in the region of the resting position of the windshieldwipers (not shown) in order to realize in this case an additional and/orseparating of the windshield 30 so that damage to fast frozen windshieldwiper blades (not shown) can be avoided when the windshield wipers (notshown) are put into operation.

[0064] If the heating layer 7 with electrically conductive plasticconsists of transparent material, then a transparent region of a windowpane, for example a windshield 30, can be provided with a correspondingsurface heating system 1. In this way fogging of a window pane outfittedin this way can be removed or avoided and even icing up can be thawed.The heat conductors currently used with rear windows, for example (notshown) could then be omitted or made smaller.

[0065] As another variation for interior space heating of a vehicle KFIGS. 5a and 5 b show the design of carpet material 33 with a surfaceheating system 1. In this sixth embodiment example, which is illustratedin FIG. 5b in a partial cross section, which should be viewed inaccordance with the direction of the arrow toward cutting plane C inFIG. 5a, the construction of such a carpet material 33 is shown. Herethe heating layer 7 with electrically conductive plastic is bonded bymeans of adhesive 25 to a lower support layer 24 as support 8.

[0066] Bristles, loops or generally fibers/threads 34 that form theupper side of the carpet material 33 can in this case be affixed eitherto the support layer 24 or can pass through the heating layer 7 withelectrically conductive plastic, can be affixed only to the layer withelectrically conductive plastic, or can originate from a special ply(not shown) which is bonded by means of adhesive 25 to the heating layer7 with electrically conductive plastic. In the latter case the supportlayer 24 can also be omitted and the support 8 can be formed by such aseparate ply (not shown).

[0067] It is also within the scope of this invention if the heatinglayer 7 with electrically conductive plastic is formed directly by thesupport layer 24, or if the heating layer 7 with electrically conductiveplastic is affixed to the support layer 24 by means of the bristles,loops, fibers or threads 34 that form the upper side of the carpetmaterial 33. Additionally it is possible to affix the heating layer 7with electrically conductive plastic to the underside of the supportlayer 24 using an adhesive 25, so that the traditional carpet material33 can otherwise be produced in the usual way and can be provided withthe surface heating system 1 subsequently. It is also possible to outfitcarpet material 33 that is already present with a surface heating system1.

[0068] As already noted, it is possible by connecting the heating layer7 with electrically conductive plastic material to a power source (notshown) to achieve a desired heating or warming effect with thecorrespondingly heated objects. Since the electrical resistance of theheating layer 7 is constant, the heating temperature can be determinedor regulated via the supplied electrical power. In an advantageous waythere is in this case the possibility of using both direct, andalternating current, in particular without producing electrosmog. Sincethe heat that is produced in this way is also exclusively radiant heat,a certain temperature and heating comfort results.

[0069] If natural raw materials such as wood fiber, sisal, banana stalkmaterial, coconut fiber, etc. are used, odor formation in wet weather aswell as bacterial attack often present serious problems. If, as with thedescribed embodiment examples, the interior panel parts are designed tobe heatable, it is possible to additionally achieve an avoidance of suchodor formation and bacterial attack in the combination of effect withthe pure warming effect.

[0070] Other specific examples for heatable objects with a surfaceheating system 1 as in this invention are, for example, a diesel tank ofplastic, where paraffining of diesel fuel at low outside temperaturescan be prevented by being able to maintain a minimum temperature, an oilbath via which motor oil can be preheated for better and more efficientoperation of the engine, an entire engine compartment, which enablespreheating of the engine, as well as, for example, a storage space bothin passenger cars as well as in trucks. Surface heating systems 1 can beadvantageously used in vehicle interiors as well as in vehicle exteriorregions.

[0071] This invention, however, is not limited to use in the field ofvehicles. All of said embodiment examples and variations as well asanalogous applications can be used, for example, with other vehiclessuch as bicycles, in the railroad, on ships and planes.

[0072] As already noted, numerous other areas of use of this inventionare possible, for instance in the case of motorcycles and mopeds theseats and operating elements can be outfitted with the correspondingsurface heating systems. Other application possibilities, for example,lie in the household (coating of plastic wallpapers, wooden ceilings,wooden floors, carpets, tiles, jackets for heating and water pipes,floor heating systems), for clothing, etc. (shoes, boots, ski boots,work clothing, protective clothing, gloves, electric blankets, warmingblankets, for example in the hospital field, warming containers), insports and recreation (sports fields with artificial turf, tent floors,sleeping surfaces in tents), as well as in the military (for instancepreheating of vehicles for better engine start in winter).

[0073] In particular, aliphatic and aromatic polyurethanes are mentionedhere only as preferred electrically conductive plastic materials orplastic materials that can be made electrically conductive.

[0074] With regard to the manufacture of a surface heating system or anobject made with such a system in accordance with the invention it ispreferable if the layer with or of electrically conductive plastic ismade in a spray or immersion process or by roller application. Acorresponding coating is preferably provided with a method for producinga heating device or an object with such a device. The invention in thisway enables in particular a matching or choice of the coating method tothe geometry of the form to be coated and/or the number of pieces to beproduced.

[0075] With the exemplary and comparable embodiments treated above thelayer thickness of the electrically conducting layer is preferablybetween about 0.05 mm and approximately 0.3 mm. If the electricallyconducting layer is also intended to satisfy a function as a visiblesurface, it is preferable if the thickness is thicker. In particular, itis also within the scope of this invention to adjust the layer thicknessin dependence on the requirement or requirement profile to the surfaceheating system or the object which can easily be found out by analysisor tests. For example, a layer thickness of 1.2 mm can be called for inthe case of a surface layer with additional function such as a vehicleinterior paneling.

[0076] As already indicated, particularly preferred specifications forthe plastic material of heating layer 7 are that it contains or consistsof polyurethane, namely preferably a crosslinked and/or one-componentpolyurethane, which is in particular UV resistant and hydrolyzable orvapor permeable.

[0077] A variation in which a seat occupancy recognition system that isin particular dependent on weight is realized with the arrangement ofthe surface heating system 1 at the same time as seat heating is aparticular specialty of this invention. Such seat occupancy recognitionsystems must today be specially realized in order to carry out, forexample, triggering of an air bag in the case of an accident only if anoccupant is sifting on a corresponding seat. Through the combinedrealization of the surface heating system 1 in accordance with thisinvention with the simultaneous function of seat occupancy recognition,which can additionally provide weight-dependent data, in order tocontrol appropriately the type and strength of an air bag triggering,not only will construction costs be saved, but also volume and weight inand on the vehicle, namely at places where it is not necessary for thestability and safety of the vehicle.

[0078] The surface heating system 1 contains in particular a stripedheating layer 7 with electrically conductive plastic, as is illustratedschematically in FIG. 6, for example. As shown, parallel strips orstripes 7 a are coated onto the support or base 8 whereas theintermediate regions 8 a are uncoated. The strips 7 a are shown only atthe lower part of the Figure, but would extend over the entire base 8 toform a heating network. Supply wires 11 and 12 connect to the strips 7 aat their opposite edges. Contact terminals 9 and 10 couple the wires 1 1and 12 to a base network and power supply. As for the rest, all thecharacteristics in accordance with the design in accordance with theembodiment example given in FIGS. 1a and 1 b are combinable andunderstandable for any specialist, so that the correspondingdescriptions are omitted here.

[0079] Indeed, not specially shown in the drawing, but nevertheless animportant use of this invention, is a mattress with a surface heatingsurface in accordance with the invention. A mattress designed in thisway has the advantage over the prior art, in which a so-called electricblanket with metallic resistance heating wires is used, that theoperating safety is at least considerably improved. A fire cannot resultwith a surface heating system in accordance with this invention. In thecase of damage to the heating layer, which can also be designed to be instrips, no sparks arise as is the case with metallic conductors.

[0080] Likewise, it was already explained above, especially inconnection with the first embodiment example, that the heating layer 7is a film or foil. Preferably, it is a varnish-like polyurethane layeror a polyurethane varnish layer with said physical properties, inparticular an enrichment with carbon dust to achieve electricalconductivity. In addition, it is preferred if it is a one-componentpolyurethane material and/or is provided with an enrichment with carbondust for electrical conductivity.

[0081] A preferred thickness of the heating layer 7 is from about 0.3 mmup to about 0.5 mm.

[0082] Instead of the spray application of the electrically conductingplastic material onto the support that was already discussed in detailabove, it is also possible to use a roller method, for example. In thiscase liquid polyurethane, for example, is applied to a roller and thenapplied to a substrate, for example the support or an externalsubstrate. The spacing of the roller surface from the substratedetermines the thickness of the heating layer. After solidification orhardening of the polyurethane, again a varnish film with the desiredproperties is obtained, where measures to shape the film, includingcutting, can be carried out during the roller application orsubsequently, as already explained above.

[0083] If the heating layer is optionally produced on the support by asuitable process, then subsequently the heating layer by itself oralready together with the support can optionally be bonded to a supportor, for example, a molded article or a covering by stitching, gluing,adhesive strips, etc., as was already discussed above.

[0084] The surface heating system can be operated with alternating ordirect current, with the response behavior being better than when directcurrent is used.

[0085] Other advantages of the surface heating system in accordance withthe invention, besides the cost advantage, over earlier systems withmetal heating wires lie in the uniform heating behavior and lower powerconsumption compared to the traditional seat heating systems withmetallic heating wires, as was shown by a series of tests.

[0086] A commercial seat heating system from the Bauerhin company (modelS4300) was compared with a surface heating system in accordance with theinvention having a heating mat of electrically conductive plastic. Theseat bottoms and seat backs were each separately controllable. Theheating mat was fastened to the seat over the head rest supports andfastened at the edge by an adhesive strip.

[0087] The measurements were intended to provide information about theheating behavior and power consumption of the two seat heating systems.Specifically the goal of the test was to determine the heat-up times forthe two designs along with the pertinent power consumption. For this aconstant voltage of 12 V was applied to the connection terminals of thetwo heating systems. The consumed current is measured via a currentmeasurement device integrated into the power supply. The temperature andcurrent are measured at intervals of 1 min. Comparison between the twoheating systems is done via the values measured at the seat. Heating matof System S4300 Conductive plastic of the Bauerhin Co. TemperatureCurrent Time in Temperature Current In ° C. in Amps minutes in ° C. inAmps 21.4 7.4 0 22.4 0.0 26.0 7.1 1 24.1 7.8 30.4 6.8 2 26.9 7.7 36.06.7 3 28.8 7.7 37.0 6.6 4 30.3 7.6 7.0 6.6 5 31.1 7.6 39.1 6.5 6 31.37.6 40.3 6.5 7 32.5 7.6 41.4 6.5 8 33.0 7.6 42.1 6.5 9 34.0 7.6 42.6 6.510 34.4 7.9 43.1 6.5 11 34.7 7.6 43.7 6.5 12 35.0 7.7 44.4 6.5 13 35.48.0 44.7 6.5 14 35.8 8.0 45.1 6.5 15 35.6 7.6 46.0 6.4 25 36.0 7.6 48.16.6 50 36.1 7.7

[0088] The temperature measurement point was approximately in the middleof the seating area for the heating mat of the surface heating system inaccordance with the invention with a heating layer having electricallyconductive plastic. With the traditional design using metallic heatingwires the temperature measurement point was 0.5 cm away from a heatingwire. The temperature at the heating wire itself after 25 min was 50° C.This temperature is necessary to achieve a surface effect. However,considerable problems are linked to this in practice, for example, thewire can burn through or the seat cover can ignite at temperatures thatare too high. These problems are eliminated with the heating surfacesystem in accordance with the invention.

[0089] Another not inconsiderable disadvantage with the traditional seatheating system is the possibly pointwise high temperature at theposition of the male genital region, which can lead to disruption offertility. The surface heating system in accordance with the inventionfundamentally does not generate any over-high temperatures, since it canin fact release heat over the entire area, and moreover can be left offof the corresponding site or decreased there.

[0090] Other tests showed that the heating behavior of the seat and backparts are approximately the same.

[0091] The superiority of the new surface heating system in accordancewith the invention over the prior design with metal conducting wiresshows up really clearly from the test results. The surface heatingsystem with the heating layer having electrically conductive plasticheats up faster and consumes less power than the traditional seatheating.

[0092] Thus, a surface heating system is created through the inventionthat can release heat over the entire area, which can be ensured betterwith a design having the heating layer consisting of the individualspaced strips mentioned above better than with the prior art, can bereversibly matched to a pressure load for a substrate, for example afoam seat cushion, and does not lead to thawing of moisture or air inuse.

[0093] Indeed, this invention, therefore, is not limited to the heatingof upholstered objects, rather the uses of the surface heating system inaccordance with the invention as heating for seating or mattresses, orin a seat, especially a vehicle seat, a mattress, are especiallypreferred and advantageous, though separate protection directed to thisis justified. The flexibility of the heating layer is of particularimportance.

[0094] Below one more preferred embodiment of the invention is explainedin more detail by means of the embodiment example shown in FIG. 7 withreference to this drawing.

[0095] By analogy with FIG. 1 a part of a surface heating system 1 thatcan be used as seat heating 4 as in FIG. 2 is shown in cross section.This surface heating system 1 contains as support 8 a polyester orpolyamide fabric with, for example, a mesh size of about 5 mm, i.e., amesh or lattice, in which the adjacent quasi parallel material strandshave a spacing of about 5 mm. The structure of the support 8 and itsmaterial is not limited to these data, but rather can be easily chosenby the specialist in correspondence with the particular mechanicalrequirements, i.e., other materials or material combinations as well asthicknesses of the material strands and other mesh sizes can also bechosen in dependence on application.

[0096] The support 8 is provided by spraying, immersion, rolling orother means with a layer of electrically conductive plastic inaccordance with the invention, as well as in the other documents. Thismeans that the material strands of the polyester or polyamide fabric arecompletely surrounded or jacketed with the electrically conductiveplastic which thus forms the heating layer 7.

[0097] As a further characteristic conductive silver or copper wires arewoven into the polyester or polyamide fabric, i.e., into support 8, at aspacing of 5-10 cm, for example, and these wires, by analogy with thefirst embodiment example as in FIG. 1, form the contact terminals 9 and10 of the power supply wires 11 and 12. Since the silver or copperwires, i.e., the contact terminals 9 and 10, also are surrounded orjacketed with the electrically conductive plastic by the spraying,immersion, rolling or other application of the layer of electricallyconductive plastic in accordance with the invention, optimum electricalcontact between them is optimally provided. The spacing of the silver orcopper wires as contact terminals 9 and 10 of the power supply wires 1 1and 12 is not limited to the range of values that are indicated, butrather can easily be selected by the specialist in correspondence withthe particular mechanical and electrical requirements, i.e., othermaterials or material combinations as well as thicknesses of the contactterminals 9 and 10 and other spacings can also be chosen in dependenceon application.

[0098] Preferably, but not as a matter of restriction, the contactterminals 9 and 10 in the case that the surface heating system 1 is aseat heat system 4, run in particular in a direction of about 90° to thedirection of driving of a vehicle (not shown). Basically the contactterminals 9 and 10 in the form of silver or copper wires can, however,run in any lengthwise or transverse direction.

[0099] A particularly preferred material composition for the heatinglayer 7, i.e., for the electrically conductive plastic, is:

[0100] 300 g rubber, which is used in the manufacture as granulate, inthis case as very fine dust,

[0101] 300 g tetrahydrofuran,

[0102] 165 g graphite, and

[0103] 300 g of a polyurethane, such as, and advantageously, 4715Lupranol from the BASF company.

[0104] This yields a total amount of 1065 g. The fractions cancorrespondingly be calculated for other amounts.

[0105] Preferred fractions for the individual components of the materialcomposition for the heating layer 7, i.e., for the electricallyconductive plastic, are:

[0106] about 20-35%, preferably approximately 25-30%, especiallypreferably about 28% of a rubber or especially a mechanically and/orelectrically equivalent or similarly acting material,

[0107] about 20-35%, preferably approximately 25-30%, especiallypreferably about 28% tetrahydrofuran or especially a mechanically and/orelectrically equivalent or similarly acting material,

[0108] about 5-25%, preferably approximately 10-20%, especiallypreferably about 15% graphite or especially a mechanically and/orelectrically equivalent or similarly acting material, and

[0109] about 20-35%, preferably approximately 25-30%, especiallypreferably about 28% of a polyurethane, for example and advantageously4715 Lupranol from the BASF company, or an especially mechanicallyand/or electrically equivalently or similarly acting material.

[0110] Another embodiment possibility of the invention is illustratedbelow. By measuring the change of power consumption of the heating layer7 a seat occupancy recognition system can be realized with particularsimplicity and advantageous. This seat occupancy recognition systemfunctions both to establish if the seat is occupied at all and also toestablish in particular the weight of the passenger who is sitting onthe seat. This aspect of this invention is on the one hand particularlyadvantageous in combination with the surface heating and on the otherhand, can also be used separately from it as a seat occupancyrecognition system by itself with a structure and characteristicsanalogous to those disclosed for the surface heating surface system inthe overall documents at hand; this seat occupancy recognition system isdeserving of protection by itself and optionally can be a component ofseparate applications for protective rights and of protective rights.

[0111] This invention was explained above in more detail by means ofembodiment examples, to which the invention is, however, not limited.All modifications, combinations, variations and substitutions of thecharacteristics illustrated above and reproduced in the drawings arewithin the range of the special knowledge of this invention. Inparticular all design possibilities that lie within the scope of thepertinent claims belong to the invention. In particular, the indicateduses of the heating devices in accordance with the invention aredisclosed and optionally are to be seen as separately deserving ofprotection.

What is claimed is:
 1. A surface heating system comprising a support anda heating layer that contains an electrically conductive plastic, whichis characterized by the fact that the heating layer is formed by aflexible film and that the support is flexible.
 2. A surface heatingsystem as in claim 1, which is characterized by the fact that thesupport is a layer, in particular a woven or nonwoven fabric, preferablya natural or synthetic nonwoven fiber material.
 3. A surface heatingsystem as in claim 1, which is characterized by the fact that theheating layer contains polyurethane, one-component polyurethane,crosslinked one-component polyurethane, a PU foam, UV-resistant and/orhydrolyzable and/or vapor-permeable plastic material, and/or theelectrically conductive plastic of the heating layer contains graphite,preferably in powder form.
 4. A surface heating system as in claim 1,which is characterized by the fact that contact terminals from powersupply wires in the heating layer or between the support and the heatinglayer are in contact with the latter.
 5. A surface heating system as inclaim 4, which is characterized by the fact that the contact terminalsof the power supply wires are affixed to the heating layer by means ofthe heating layer itself.
 6. A surface heating system as in claim 4,which is characterized by the fact that the contact terminals of thepower supply wires are stitched or glued to the heating layer and/or thesupport.
 7. A surface heating system as in claim 1, which ischaracterized by the fact that the heating layer is formed directly onthe support by spraying, rolling or spreading.
 8. A surface heatingsystem as in claim 1, which is characterized by the fact that theheating layer is glued, stitched or welded to the support.
 9. A surfaceheating system as in claim 1, which is characterized by the fact thatthe support is a molded article of an elastic material.
 10. A surfaceheating system as in claim 9, which is characterized by the fact thatthe molded article is a seat cushion of a seating surface or a seat backor a cushion of furniture for sitting or reclining, in a particular amattress.
 11. A surface heating system as in claim 1, which ischaracterized by the fact that manually and/orelectrically/electronically controllable and/or automatic currentcontrol system is provided, which can be connected to a power source andis connected to the power supply wires, whose contact terminals are incontact with heating layer.
 12. A surface heating system as in claim 1,which is characterized by the fact that the support is formed by a wovenfabric, which is preferably a polyester or polyamide fabric and/or has amesh size of about 5 mm.
 13. A surface heating system as in claim 12,which is characterized by the fact that contact terminals from powersupply wires are woven into the fabric and preferably have a spacing of5-10 cm and/or are formed of silver or copper wires.
 14. A surfaceheating system as in claim 12, which is characterized by the fact thatthe support is provided with the heating layer by spraying, immersion,rolling or another method, i.e., it is provided with a layer of anelectrically conductive plastic, so that preferably the support and/orthe contact terminals are completely surrounded or jacketed with theelectrically conductive plastic.
 15. A surface heating system as inclaim 1, which is characterized by the fact that the materialcomposition for the heating layer, i.e., for the electrically conductiveplastic, contains: about 20-35%, preferably approximately 25-30%,especially preferably about 28% of a rubber or in particular amechanically and/or electrically equivalent or similarly actingmaterial, about 20-35%, preferably approximately 25-30%, especiallypreferably about 28% tetrahydrofuran or in particular a mechanicallyand/or electrically equivalent or similarly acting material, about5-25%, preferably approximately 10-20%, especially preferably about 15%graphite or in particular a mechanically and/or electrically equivalentor similarly acting material, and about 20-35%, preferably approximately25-30%, especially preferably about 28% of a polyurethane, for exampleand preferably 4715 Lupranol (BASF), or in particular a mechanicaland/or electrically equivalent or similarly acting material.
 16. Asurface heating system as in claim 1, which is characterized by the factthat the material composition for the heating layer, i.e., for theelectrically conductive plastic, contains: about 30-70%, preferablyapproximately 50% graphite or in particular a mechanically and/orelectrically equivalent or similarly acting material, and about 70-30%,preferably approximately 50% of an aqueous polyurethane binder, andoptionally a remainder.
 17. A surface heating system as in claim 16,which is characterized by the fact that the remainder contains rubber.18. A surface heating system as in claim 1, which is characterized bythe fact that the material composition for the heating layer containscarbon fibers.
 19. A surface heating system with a heating layer, whichis characterized by the fact that the heating layer contains carbonfibers and is flexible.
 20. A surface heating system as in claim 19,which is characterized by the fact that the heating layer consists ofcarbon fibers.
 21. A surface heating system as in claim 19, which ischaracterized by the fact that a woven or nonwoven material or fibernonwoven material is formed from the carbon fibers of the heating layer,especially in a ribbon-like or flat embodiment.
 22. A surface heatingsystem as in claim 19, which is characterized by the fact that threadsare formed from the carbon fibers of the heating layer and from thesethreads a woven or knit material or fiber nonwoven material or a net isformed, in particular in a ribbon-like or flat embodiment.
 23. Aheatable object, comprising a surface heating system as defined inclaim
 1. 24. A heatable object as in claim 23, which is characterized bythe fact that the object is a seat bottom or a seat back or a cushion offurniture for sitting or reclining, in particular a mattress, and thatpreferably the heating layer is anatomically matched to thethigh/buttocks regions and/or back regions of a user.
 25. A heatableobject as in claim 24, which is characterized by the fact that theheating layer is anatomically molded in the level of the seat bottom orthe seat back or the cushion of furniture for sitting or reclining, inparticular a mattress, in that it is present or electrically conductiveonly in accordance with anatomical guidelines.
 26. A heatable object asin claim 24, which is characterized by the fact that the heating layerhas a thickness profile corresponding to anatomically matched heatrelease.
 27. A heatable object as in claim 23, which is characterized bythe fact that the object is an upholstered covering, especially of avehicle.
 28. A heatable object as in claim 27, which is characterized bythe fact that the surface heating system for heating the object isdesigned to produce a different release of heat over its area.
 29. Aheatable object as in claim 23, which is characterized by the fact thatthe heating layer is profiled over its areal extent and/or in itsthickness for heat release that differs over its area.
 30. A method forproducing a surface heating system comprising the steps of bonding aheating layer with electrically conductive plastic is to a support,which is characterized by the heating layer being formed by firstapplying an electrically conductive, especially a foaming or foamplastic material onto a support and then hardening the plastic materialon the support.
 31. A method as in claim 30, which is characterized bythe fact that before the application of the electrically conductive,especially foaming or foam plastic material onto the support, contactterminals from power supply wires are first arranged on the side of thesupport on which the plastic material is then applied.
 32. A method forproducing a surface heating system, where a heating layer withelectrically conductive plastic is bonded to a carrier, which ischaracterized by the fact that the heating layer is made from anelectrically conductive, especially a foaming or foam plastic materialand then arranged on the support.
 33. A method as in claim 32, which ischaracterized by the fact that the heating layer after being arranged onthe support is bonded to it without the possibility of slipping.
 34. Amethod as in claim 33, which is characterized by the fact that theheating layer is stitched, glued or welded to the support.
 35. A methodas in claim 30, which is characterized by the fact that an electricallyconductive polyurethane is used as plastic material.
 36. A method as inclaim 30, which is characterized by the fact that the contact terminalsof power supply wires are arranged on the heating layer and/or thesupport so that in the bond of support and heating layer they are incontact with the latter.
 37. A method as in claim 36, which ischaracterized by the fact that the contact terminals from the powersupply wires are stitched or glued to the heating layer and/or thesupport.
 38. A method as in claim 30, which is characterized by the factthat the heating layer is profiled in its areal shape and/or thicknessduring or after its manufacture.
 39. A method for producing a surfaceheating system, where a heating layer with electrically conductiveplastic is bonded to a support, which is characterized by the fact thata woven fabric is made as support, contact ends from power supply wiresare woven into the fabric when it is made or subsequently, and then aheating layer is applied to the support and the contact ends.
 40. A seatoccupancy recognition system, which is characterized by the fact that itcontains elements of electrically conductive plastic.
 41. A seatoccupancy recognition system as in claim 40, which is characterized bythe fact that it contains strips of electrically conductivepolyurethane.
 42. A seat occupancy recognition system as in claim 40,which is characterized by the fact that the electrically conductiveplastic contains 50-70%, especially 55-60% and preferably about 58%graphite and 30-50%, especially 40-45% and preferably approximately 42%PU.
 43. A seat occupancy recognition system as in claim 40, which ischaracterized by the fact that it contains devices for recognitionand/or processing a change of resistance in the electrically conductiveplastic.
 44. A seat occupancy recognition system as in claim 40, whichis characterized by the fact that the material composition for thestrips contains: about 30-70%, preferably approximately 50% graphite ora material that is particularly mechanically and/or electricallyequivalent or similarly acting, and about 70-30%, preferablyapproximately 50% of an aqueous polyurethane binder, and optionally aremainder.
 45. A seat occupancy recognition system as in claim 44, whichis characterized by the fact that the remainder contains rubber.
 46. Aseat occupancy recognition system as in claim 40, which is characterizedby the fact that the material composition for the heating layer containscarbon fibers.
 47. A seat occupancy recognition system, which ischaracterized by the fact that it contains elements with carbon fibers.48. A seat occupancy recognition system as in claim 47, which ischaracterized by the fact that the elements are in the form of strips,and/or the elements consist of carbon fibers.
 49. A seat occupancyrecognition system as in claim 46, which is characterized by the factthat a woven or knit material or fiber nonwoven material is formed fromthe carbon fibers of the elements or strips, in particular in a ribbonor flat embodiment.
 50. A seat occupancy recognition system as in claim46, which is characterized by the fact that threads are formed from thecarbon fibers of the strips and from these a woven or knit material orfiber nonwoven material or a network is formed, especially in a ribbonor flat embodiment.
 51. A seat with seat occupancy recognition system,which is characterized by the fact that the seat occupancy recognitionsystem is designed as in claim
 40. 52. A seat occupancy recognitionmethod, which is characterized by the fact that a change of resistancein an electrically conductive plastic material as a consequence of aweight applied to the material is detected.